AQM Stability in Multiple Bottleneck Networks

In this paper, we highlight that multiple bottleneckscan affect the performance of Active Queue Management controllers,which are usually configured on a single bottleneck basis,as if each controller were the only element regulating the TCPtraffic along its path. To see this, we consider a network scenariowhere RED is configured at each router, according to previouslydeveloped control theoretic techniques. These configuration rulesassure stability in a single bottleneck scenario. Yet, we showthat instability may arise when two link become congested. Wejustify this result through a multiple bottleneck model and giveguidelines for new cooperative AQM controllers.